64 層螺旋CT 的層敏感度曲線測(cè)試
劉傳亞 秦維昌 王巍 盧傳友
【摘要】 目的 測(cè)試和評(píng)價(jià)64 層螺旋CT 的層敏感度曲線( SSP) 及有效層厚半高寬( FWHM) 。
方法 對(duì)Somatom Sensation 64 層螺旋CT, 使用臨床常用的腹部螺旋掃描模式和CT 質(zhì)控delta ( δ) 體
模, 分別以螺距( pitch) = 0. 50、0. 75、1. 00、1. 25、1. 50, 重建層厚0. 6 mm( 標(biāo)稱值) 進(jìn)行掃描和重建。
對(duì)于pitch = 1. 00, 再分別以層厚1. 0、1. 5 mm 進(jìn)行重建。然后測(cè)試各種情況的SSP 和有效層厚。
結(jié)果 對(duì)于標(biāo)稱層厚0. 6 mm, 不同pitch 時(shí)測(cè)試的有效層厚分別為0. 67、0. 67、0. 66、0. 69、0. 69 mm;
pitch = 1. 00 時(shí), 標(biāo)稱層厚0. 6、1. 0、1. 5 mm 的有效層厚分別為0. 66、1. 06、1. 52 mm。有效層厚均略
大于標(biāo)稱層厚, 但與標(biāo)稱層厚相比均不超過0. 1 mm。測(cè)試的SSP 形狀近似鐘形, 左右分布基本對(duì)稱,
沒有延伸較長(zhǎng)的尾部; 隨著重組層厚的增加, SSP 逐漸變平闊; 當(dāng)pitch 改變時(shí), SSP 變化輕微。結(jié)論
對(duì)于Sensation 64 層螺旋CT, pitch 的變化對(duì)SSP、有效層厚和z 軸空間分辨率的影響很小。這一結(jié)論
有助于臨床應(yīng)用中優(yōu)化CT 掃描方案。
【關(guān)鍵詞】 體層攝影術(shù), X 線計(jì)算機(jī); 評(píng)價(jià)研究
Measurement of slice sensitivit y pr ofile for a 64-slice spir al CT system LIU Chuan-ya * , QIN Weicha
ng, WANG Wei, LU Chuan-you. * Shandong Provincial Medical Ima ging Research Institute, J inan
250021, China
Corresponding author: QIN Wei-chang, Email: qin_wch@sina. com
【Abstra ct 】 Object ive To measure and evaluate slice sensitivity profile ( SSP) and the full width at
half-maximum( FWHM) for a 64-slice spiral CT system. Methods Using the same CT technique and body
mode as those used for clinical CT, delta phantom was scanned with Somatom Sensation 64-slice spiral CT.
SSPs and FWHM were measured both with reconstruction slice width of 0. 6 mm at pitch = 0. 50, 0. 75,
1. 00, 1. 25, 1. 50 and with reconstruction slice width of 0. 6, 1. 0, 1. 5 mm at pitch = 1 respectively.
Results For normal slice width of 0. 6 mm, the measured FWHM, i. e. effective slice width, is 0. 67,
0. 67, 0. 66, 0. 69, 0. 69 mm at different pitch. All the measured FWHM deviate less than 0. 1mm from the
nominal slice width. The measured SSPs are symmetrical, bell-shaped curves without far-reaching tails, and
show only slight variations as a function of the spiral pitch. When reconstruction slice width increase,
relative SSP become wider. Conclusions The variation of pitch hardly has effect all on SSP, effective slice
width, and z-direction spatial resolution for Sensation 64-slice spiral CT system, which is helpful to optimize
CT scanning protocol.
【Key wor ds】 Tomography, X-ray computed; Evaluation study

64 層螺旋CT 的層敏感度曲線測(cè)試--普通.rar